Photocurable dental materials are cured by exposure to radiant energy in a preselected spectral range in either the ultraviolet or visible spectrum. The materials are used by dentists intraorally as a replacement for gold, porcelain, or silver amalgam to fill cavities and to repair chipped or broken teeth, as well as to coat teeth for cosmetic reasons. The radiant energy is transmitted from a lamp in a lamp assembly through an optic light guide. To subject the dental material to the maximum available light energy, the distal end of the optic light guide is positioned as close as possible to the photocurable material in the dental restoration. Best results are achieved when the light is uniformly applied over the entire surface area of the material to be cured. However, the surface area varies with the size of the restoration and is, in general, larger for posterior restorations, as compared with anterior restorations. In addition, small diameter light guides are generally required to reach areas which would otherwise be inaccessible, such as the gingival floor of posterior restorations. Accordingly, maximum power distribution and intensity, i.e., power density is assured when the surface area is matched to the optics of the light curing unit.
The foregoing is accomplished in accordance with the present invention using a light curing assembly and a plurality of interchangeable autofocus light guides having preselected diameters corresponding to typical surface area variations and a matched preselected length to provide optimum spacing relative to the focal point of the curing lamp. The autofocus light guides are adapted to be interchangeably inserted into the light-curing assembly to provide maximum power density independently of the selection of the autofocus light guide.